Upon his accession to the throne, Sheshonq III adopted the prenomen of Ramesses II (with a slight variant - Setepenamun instead of Setepenre) to his name, as well as 'Beloved of Amun' as well as 'Son of Bast' and 'god, Ruler of Heliopolis.
At the start of the reign Sheshonq III had the learned the mistakes of the past and accepted the demands of the Thebans for the choice of their own High Priest and southern governor - in return for this they accepted (for a while) Sheshonq III as their legitimate king. It is at this period that some inscriptions have been found naming Harsiese as High Priest at Thebes. Egypt's unity was not to last - in Year 8 another contender for the throne was to appear, this time it was not Thebes that was to threaten the power of the pharaoh, this time the threat came within Tanis itself - a new king surfaced, King Pedubast (I) (later founder of the 23rd Dynasty).
Although ruling alongside Shoshenq III, Pedubast was different from the co-ruling High Priests of the past in that he had his own regnal years (something the High Priests had never done), he ruled from a separate Delta capital - Leontopolis, he also named his co-regent as being Iuput I. Thus there were two competing pharaohs of Egypt, something which the High Priest were ready to accept in their desire to break free from the yolk of Tanis. Evidence of such a conflict is shown by an inscription dating to this period: the name of the High Priest Harsiese B accompanies the name of Pedubast I, with a date of Year 5. The name of Shoshenq III is missing, just his regnal year (Year 12) is written. No other inscriptions of Shoshenq III (nor his successors) are then found in the south of the country (the only exception being Shoshenq III's brother - Prince Osorkon).
Buildings of Shoshenq III
At Tanis Shoshenq III added to the Great Temple of Amun (by building a massive pylon-gateway of granite through the main enclosure wall). Outside Tanis he built at several place through the Delta - at Mendes he built a chapel, at Tell Umm Harb (ancient Mosdai) he built a chapel, at Kom el Hisn he added a gateway to the temple and at Memphis the remains of a chapel to Sekhmet have been found.
Also at Tanis, Shoshenq III built his own tomb near those of his predecessors.
The Royal Family
His Queen : Tentamenopet ('Royal Wife'. 'Great Chief Queen of His Majesty'), who had a daughter : Ankhesenshoshenq.
Three sons are known: Bakennefi A (heir to the throne: 'Great Prince, Chief of the Two Lands, Eldest King's Son of the Lord of the Two Lands, Army Leader.
The second son : Pashedbast B (died before Shoshenq III)
Third son : Pimay ('Great Chief of the Ma, son of the Lord of the Two Lands, Shoshenq'), this is possibly the 'Pimay' that succeeded Shoshenq III.
Fourth son : Takeloth C ('Son of the Lord of the Two Lands'), his mother was Djedbastesankh.
(possible) Fifth son : Padebenhenbast ('High Priest of Amenresonter, King's Son of Ramesses, Mek-prince of Pawer ..., Army Leader').
The end of the reign
Shoshenq III did live to reign a long time - well over thirty years, but by the end of his reign not only were there effectively two pharaohs ruling in Egypt, but the various chieftains of the Ma across the Delta were slowly acquiring authority and power and forming close family dynasties of their own.
When Shoshenq III died he was buried in his tomb in Tanis and was succeeded by the short-lived Pimay.